This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We propose to study the organization of segrosome, the cellular apparatus for chromosome segregation in human pathogen Mycobacterium tuberculosis. Two proteins (ParA and ParB) and a set of original-proximal DNA sequences (parS) form the segrosome machinery. ParA is a motor protein that drives this process. ParB forms a nucleo-protein complex with the parS DNA sequence and polymerize on the parS-proximal DNA scaffold to form a superstructure. Our aim is to elucidate the three-dimensional organization of this nucleoprotein complex for the segrosome of M. tuberculosis. X-ray solution scattering data (SAXS) obtained from SSRL will be combined with additional experimental data and homology modeling approach to build a model of the ParB-parS complex and the nucleoprotein filament.